Abstract:

The invention discloses a wireless communication system including first
mobile devices, a second mobile device, and a system end. The system end
cooperates with the second device to determine a coordinate of each of
the first mobile devices. When each of the first mobile devices receives
a signal from the system end, each of the first mobile devices can detect
its corresponding received signal strength. The system end or the second
mobile device is capable of generating a received signal strength
distribution map according to the coordinates and the strengths of the
received signals.

Claims:

1. A wireless communication system, comprising:a plurality of first mobile
devices;a second mobile device; andat least one system end cooperating
with the second mobile device to determine a coordinate for each of the
first mobile devices;wherein when each of the first mobile devices
receives a signal from the at least one system end, each of the first
mobile devices is capable of detecting a corresponding received signal
strength (RSS), when each of the first mobile devices receives signals
from the at least one system end, the coordinate corresponds to the
strongest RSS of the system end, the first mobile device is capable of
automatically generating an RSS distribution map according to the
coordinates, the at least one system end, and the strongest RSSs
corresponding to the at least one system end.

2. The wireless communication system of claim 1, wherein the system end is
a base station.

3. The wireless communication system of claim 1, wherein the system end
has at least one wireless positioning algorithm selected from a group
consisting of: time of arrival (TOA) algorithm, time difference of
arrival (TDOA) algorithm, direction of arrival (DOA) algorithm, and RSS
algorithm.

4. The wireless communication system of claim 1, wherein the second mobile
device has at least one wireless positioning algorithm selected from a
group consisting of: TOA algorithm, TDOA algorithm, and RSS algorithm.

5. The wireless communication system of claim 1, wherein according to the
coordinates and the RSSs, the system end or the second mobile device
utilizes a least squares method to calculate a RSS, and the RSS
corresponds to a target coordinate of the RSS distribution map.

6. The wireless communication system of claim 3, wherein according to the
RSS distribution map, the system end is capable of selectively enabling
or disabling the at least one wireless positioning algorithm.

7. The wireless communication system of claim 4, wherein according to the
RSS distribution map, the second mobile device is capable of selectively
enabling or disabling the at least one wireless positioning algorithm.

8. A wireless communication system, comprising:a plurality of first mobile
devices;three second mobile devices, each of the second mobile devices
cooperating with each other to determine a coordinate of each of the
first mobile devices; anda system end;wherein when each of the first
mobile devices receives a signal from the system end, each of the first
mobile devices is capable of detecting a corresponding received signal
strength (RSS), the system end or each of the second mobile devices is
capable of automatically generating an RSS distribution map according to
the coordinates and the RSSs.

9. The wireless communication system of claim 8, wherein the system end is
a base station.

10. The wireless communication system of claim 8, wherein the system end
has at least one wireless positioning algorithm selected from a group
consisting of: time of arrival (TOA) algorithm, time difference of
arrival (TDOA) algorithm, direction of arrival (DOA) algorithm, and RSS
algorithm.

11. The wireless communication system of claim 8, wherein each of the
second mobile devices has at least one wireless positioning algorithm,
respectively, selected from a group consisting of: time of arrival (TOA)
algorithm, time difference of arrival (TDOA) algorithm, and RSS
algorithm.

12. The wireless communication system of claim 8, wherein according to the
coordinates and the RSSs, the system end or the second mobile device
utilizes a least squares method to calculate a RSS, the RSS corresponds
to a target coordinate of the RSS distribution map.

13. The wireless communication system of claim 11, wherein according to
the RSS distribution map, the system end is capable of selectively
enabling or disabling the at least one wireless positioning algorithm.

14. The wireless communication system of claim 12, wherein according to
the RSS distribution map, the second mobile device is capable of
selectively enabling or disabling the at least one wireless positioning
algorithm.

Description:

BACKGROUND OF THE INVENTION

[0001]1. Field of the Invention

[0002]The invention relates to a wireless communication system, and
particularly, to a wireless communication system for automatically
generating a received signal strength (RSS) distribution map.

[0003]2. Description of the Prior Art

[0004]In recent years, the wireless communication positioning technology
is full of vitality, and the application range of the technology has also
become broader and broader. For example, the positioning technology can
be applied to a navigating system, a user position information
management, a mobile emergency positioning (e.g., the related positioning
requirement of the mobile for the E-911 law in the United States), a
logistics management, and a motorcade mobilization.

[0005]In general, a received signal strength (RSS) distribution map will
be established beforehand for positioning the mobile devices. At present,
a fingerprint method is usually used for establishing the RSS
distribution map. When the fingerprint method is used for establishing
the RSS distribution map, a map that contains the entire positioning
environment is needed, and the fingerprint is sampled by an electronic
device which can detect signals in the entire positioning environment.
When the positioning environment is very large, it takes a lot of time
and cost to establish the RSS distribution map by the fingerprint method.
Besides, positioning errors will occur when the positioning environment
changed while the RSS distribution map formerly established is not
updated.

[0006]Therefore, the scope of the invention is to provide a wireless
communication system for automatically generating a RSS distribution map.

SUMMARY OF THE INVENTION

[0007]A scope of the invention is to provide a wireless communication
system for automatically generating a RSS distribution map.

[0008]According to a preferred embodiment, the wireless communication
system of the invention comprises a plurality of first mobile device, a
second mobile device, and a system end. The system end cooperates with
the second mobile device to determine a coordinate of each of the first
mobile devices. When each of the first mobile devices receives a signal
from the system end, each of the first mobile devices is capable of
detecting a corresponding RSS. The system end or the second mobile device
is capable of automatically generating a RSS distribution map according
to the coordinates and the RSSs.

[0009]Thus, the function of the wireless communication system of the
invention is to use the coordinates and the RSS of the mobile devices to
automatically generate the RSS distribution map. By doing so, the mobile
device can fastly determine the coordinate of the mobile device itself
via the RSS distribution map.

[0010]The advantage and spirit of the invention may be understood by the
following recitations together with the appended drawings.

BRIEF DESCRIPTION OF THE APPENDED DRAWINGS

[0011]FIG. 1 is a functional block diagram of the wireless communication
system in the first preferred embodiment according to the invention.

[0012]FIG. 2 is a diagram of the RSS distribution map automatically
generated by the wireless communication system in FIG. I.

[0013]FIG. 3 is a diagram of the wireless communication system in FIG. 1
positioning the first mobile device.

[0014]FIG. 4 is a diagram of the wireless communication system in FIG. 1
positioning the first mobile device in another preferred embodiment
according to the invention.

[0015]FIG. 5 shows the connecting range of three different system ends.

[0016]FIG. 6 is a diagram of the RSS distribution map generated by the
coordinates, system ends, and RSSs.

DETAILED DESCRIPTION OF THE INVENTION

[0017]Please refer to FIG. 1 and FIG. 2. FIG. 1 is a functional block
diagram of the wireless communication system 1 of a preferred embodiment
according to the invention. FIG. 2 is a diagram of the RSS distribution
map 3 automatically generated by the wireless communication system 1. As
shown in FIG. 2, the RSS distribution map 3 is a distribution map of the
coordinates with respect to the RSS and used for determining the
coordinates according to the RSSs. In the embodiment, the wireless
communication system 1 is used to automatically generate the RSS
distribution map 3.

[0018]As shown in FIG. 1, the wireless communication system 1 comprises a
plurality of first mobile devices 10, a second mobile device 12, and a
system end 14. The system end 14 can be a base station, but it is not
limited to that. The first mobile device 10 and the second mobile device
12 can be a notebook, a PDA, a navigating device, a mobile, or other
similar mobile devices. The system end 14 has at least one wireless
positioning algorithm selected from a group consisting of: time of
arrival (TOA) algorithm, time difference of arrival (TDOA) algorithm,
direction of arrival (DOA) algorithm, RSS algorithm, and other similar
wireless positioning algorithm. The second mobile device 12 has at least
one wireless positioning algorithm selected from a group consisting of:
TOA algorithm, TDOA algorithm, RSS algorithm, and other similar wireless
positioning algorithm. When the first mobile device 10 receives the
signal from the system end 14, the first mobile device 10 can detect the
corresponding RSSs.

[0019]Please refer to FIG. 3. FIG. 3 is a diagram of the wireless
communication system 1 in FIG. 1 positioning the first mobile device 10.
In the embodiment, the system end 14 cooperates with the second mobile
device 12 to determine the coordinates of each of the first mobile
devices 10. As shown in FIG. 3, a coordinate system 2 is established in
advance by the system end 14. The system end 14 is at the original point
of the coordinate system 2, and the coordinate system 2 has a X axis and
a Y axis. Then, the system end 14 can use TOA algorithm, TDOA algorithm,
or RSS algorithm to determine the distances LA1-LAn between the system
end 14 and each of the first mobile devices 10. And, DOA algorithm is
used to determine the angles θ1-θn corresponding to the X
axis or the Y axis for each of the first mobile device 10. In the
embodiment, the coordinate CB1 of the second mobile device 12 is already
known. The second mobile device 12 can use TOA algorithm, TDOA algorithm,
or RSS algorithm to determine the distances LB1-LBn between the second
mobile device 12 and each of the first mobile devices 10. The system end
14 can determine the coordinates C1-Cn of each of the first mobile
devices 10 on the coordinate system 2 according to the distances LA1-LAn
between the system end 14 and each of the first mobile devices 10, the
angles θ1-θn, each of which the first mobile device 10
corresponds to the X axis or the Y axis, and the distances LB1-LBn
between the second mobile device 12 and each of the first mobile devices
10. By doing that, the coordinates C1-Cn of each of the first mobile
devices 10 can be obtained. It should be noticed that the function of the
second mobile device 12 is to cooperate with the system end 14 for the
more accurate positioning of the first mobile device 10. Besides, the
number of the second mobile device 12 can be larger than 1 to increase
the efficiency and the accuracy of positioning.

[0020]When each of the first mobile devices 10 receives the signal from
the system end 14, each of the first mobile devices 10 would detect the
corresponding RSSs. Then, each of the first mobile devices 10 can
transmit the corresponding RSS to the system end 14 or the second mobile
device 12. Thus, the system end 14 or the second mobile device 12 can
automatically generate the RSS distribution map 3 as shown in FIG. 2
according to the coordinates C1-Cn and the corresponding RSSs of each of
the first mobile devices 10.

[0021]Please refer to FIG. 4. FIG. 4 is a diagram of the wireless
communication system 1 in FIG. 1, positioning the first mobile device 10
of another preferred embodiment according to the invention. In the
embodiment, the wireless communication system 1 has three second mobile
devices 12. Each of the second mobile devices 12 respectively has at
least one wireless positioning algorithm selected from a group consisting
of: TOA algorithm, TDOA algorithm, RSS algorithm, and other similar
wireless positioning algorithm. The coordinates CB1-CB3 of the second
mobile devices are already known. As shown in FIG. 4, the three second
mobile devices 12 can use TOA algorithm, TDOA algorithm, or RSS
algorithm, and cooperate with a triangle positioning algorithm to
determine the coordinates C1-Cn of the first mobile devices. The triangle
positioning algorithm can be easily achieved by those who knows the prior
art well. It is not unnecessarily described here. In practical
applications, the number of the second mobile devices 12 can be larger
than 3 to increase the efficiency and the accuracy of positioning.

[0022]When each of the first mobile devices 10 receives the signal from
the system end 14, each of the first mobile devices 10 would detect the
first corresponding RSS. Then, each of the first mobile devices 10 can
transmit the first corresponding RSS to 4 the system end 14 or the second
mobile device 12. Thus, the system end 14 or the second mobile device 12
can automatically generate the RSS distribution map 3 as shown in FIG. 2,
according to the coordinates C1-Cn of the first mobile devices 10 and the
RSSs of the first mobile devices 10.

[0023]The RSS distribution map 3 is used for positioning the target mobile
device (not shown in the figure). When the target mobile device receives
the signals from the system end 14, the target mobile device will detect
the corresponding RSS. Then, the target mobile device can determine the
coordinates of the target mobile device according to the RSSs and the RSS
distribution map 3. It should be noticed that when the larger the number
of the first mobile device becomes, the more accurate the positioning
method using the RSS distribution map 3 is. In addition, when the RSS
distribution map 3 is not accurate enough to determine the coordinate of
the target mobile device, the wireless positioning algorithm of the
system end 14 and/or the second mobile device 12 can be cooperated to
determine the coordinate of the target mobile device more accurately.

[0024]In practical applications, when the target coordinate (not shown in
the figure) of the RSS distribution map 3 lacks the corresponding RSS,
the system end 14 or the second mobile device 12 can calculate the RSS
corresponding to the X value of the target coordinate and the RSS
corresponding to the Y value, respectively, according to the coordinates
in the RSS distribution map 3 and the corresponding RSS by using the
least squares method. Then, an average RSS is obtained by averaging the
RSS corresponding to the X value of the target coordinate and the RSS
corresponding to the Y value to be the RSS of the target coordinate. When
the first mobile device 10 is moved to the target coordinate, the RSS
calculated by the least squares method is replaced by the real RSS.

[0025]In practical applications, when a new first mobile device 10 is
added to the wireless communication system 1, or when the first mobile
device 10 is moved to different coordinates, the RSS distribution map 3
can be updated by the wireless communication system 1 to ensure more
accurate positioning, and it will not be affected by the change of the
environment. In addition, when the RSS distribution map 3 has enough
coordinates and RSSs as samples, the wireless positioning function of the
system end 14 and/or the second mobile device 12 can be selectively
stopped temporarily to save on the electricity cost. For example, the
second mobile device 12 can selectively enable or disable the wireless
positioning function of the second mobile device 12 any time according to
the integrity of the RSS distribution map 3 in the positioning range of
the second mobile device 12 to save on the electricity cost. The
positioning range of the second mobile device 12 depends on the wireless
standard used in the second mobile device 12. For example, the
positioning range of the UWB and the bluetooth is 10 meters; the
positioning range of the 802.11b/g area network is 50-100 meters. It
should be noticed that the wireless standard used in the second mobile
device 12 is not limited to that.

[0026]Please refer to FIG. 5. When a mobile device (not shown in FIG. 5)
is in a region covered by a plurality of system ends 14 (FIG. 5 shows
only three system ends 14), an RSS distribution map with higher accuracy
can be generated according to the invention. As shown in FIG. 5, the
connecting ranges of three different system ends are represented by three
circles with dotted line. The different regions covered by the three
system ends 14 are represented as A, B, C, D, respectively. The three
system ends 14 are connected with each other by network. When the mobile
device moves randomly in the-regions A, B, C, or D, it is capable of
communicating with each system end 14 respectively.

[0027]The mobile device is capable of recording the RSSs of different
system ends in the common regions A, B, C, D, and the RSS is the
strongest among the regions. Please refer FIG. 6. FIG. 6 is a diagram of
the RSS distribution map generated by the coordinates, system ends, and
RSSs. The method is not limited by the above RSS distribution map
corresponding to single system end. That is to say, when a plurality of
system ends covers a region jointly, the invention can position the
mobile device more accurate. Furthermore, the invention can keep the best
connecting state when the mobile device connects to the system end.

[0028]Compared to the prior art, the wireless communication system of the
invention is to use the coordinates of the mobile devices and the RSSs of
the mobile devices for automatically generating the RSS distribution map
3. In this way, the mobile device can promptly determine the coordinate
of the mobile device itself by the RSS distribution map. Due to the
number of the mobile device becomes larger and larger, the wireless
communication system of the invention will be more efficient and
cost-effective for establishing the RSS distribution map. In addition, by
updating the RSS distribution map, the wireless communication system of
the invention makes the positioning more accurate and would not be
affected by the change of the environment.

[0029]With the example and explanations above, the features and spirits of
the invention will be hopefully well described. Those skilled in the art
will readily observe that numerous modifications and alterations of the
device may be made while retaining the teaching of the invention.
Accordingly, the above disclosure should be construed as limited only by
the metes and bounds of the appended claims.